A prior-art washing/drying machine having a drying function is configured such that air in a washing tub in which garment is contained is heated by circulating the air from the washing tub through a drying air duct and, for dehumidification of hot and wet air flowing out of the washing tub, water is supplied into the drying air duct and heat-exchanged with the air in a drying process (see, for example, Patent Documents 1, 2 and 3).
Patent Document 1 proposes an arrangement which includes a water-cooled dehumidifier typically requiring about 6-liter water for dehumidification, and is configured such that bathwater is supplied as dehumidification water and, when the bathwater is exhausted, the drying process is continued by using tap water (see paragraphs [0003] to [0005] in Patent Document 1).
Patent Document 2 proposes a technique of controlling the supply amount of dehumidification water to be supplied for heat exchange based on a difference between the temperature of hot air flowing out of a washing tub before the heat exchange and the temperature of the dehumidification water after the heat exchange with the hot air without excess and deficiency of the dehumidification water, while ensuring effective dehumidification (see [SUMMARY] and paragraphs [0003] to [0008] and [0020] in Patent Document 2).
Patent Document 3 proposes a technique of performing an intermittent cooling water supply control by detecting the temperature of air taken out of a washing tub and heat-exchanged with cooling water and the temperature of the cooling water after the heat exchange with the air, calculating the average of the temperatures, and supplying the cooling water for the heat exchange based on the average in order to ensure higher drying capability and reduction of the consumption of the cooling water for water saving (see [SUMMARY] and [Claim 1] in Patent Document 3).    Patent Document 1: JP-A-2002-35492    Patent Document 2: JP-A-2003-236290    Patent Document 3: JP-A-2006-247185